I have a 300SD built Oct 83. It has a 500mA draw on the battery that will flatten the battery if you don't drive it for 4 or 5 days. I traced it down to something associated with the power seat circuit. The draw goes away if I pull the relay associated with the power seats. There are two of them one is labeled Isolation relay or some such. I pulled the one closes to the center of the car. I thought maybe is was a sticking relay but I swapped it with the aux fan relay but same problem remains.

Any ideas?

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98 E320 4matic Wagon
84 300SD (2 ea.)
51 Chev 1-ton PU
Assorted old motorcycles